[Hitachi] recently showed a prototype of an RFID chip measuring a .05 millimeters square and 5 microns thick, about the size of a grain of sand. They expect to have ‘em on the market in two or three years.

The chips are packed with 128 bits of static memory, enough to hold a 38-digit ID number.

The size make the new chips ideal for embedding in paper, where they could verify the legitimacy of currency or event tickets. Implantation under the skin would be trivial…